The present invention relates to angular position transducers having simple and maintenance-free construction which can be widely used in the equipment requiring position control such as machine tools, robots, and factory automation machines.
Hitherto, rotary encoders, resolvers and synchros have been used as angular position transducers for the above mentioned equipment. However, optical rotary encoders increase the error when used in humid or dirty environments and are expensive, especially those of the absolute type. On the other hand, conventional brushless resolvers and synchros are also expensive due to their intricate construction, wherein a rotary transformer supplies current to the exciting coils wound on the rotor poles. In order to solve these problems, variable-reluctance resolvers and synchros requiring no rotary transformers, where both exciting and output coils are wound onto a stack of magnetic stator laminations and therefore the stack of rotor magnetic laminations carry no windings, have been investigated. However, until now variable-reluctance resolvers and synchros with high accuracy have not been put into practical use.
As stated above, the conventional resolvers and synchros are expensive due to the intricate construction wherein the rotary transformer supplies the exciting windings with the current, and the variable-reluctance ones of simple construction have not been widely used because of their inferior accuracy. Therefore, the most important problem involved with the variable-reluctance resolvers and synchros is how to improve the accuracy. In order to solve this problem, the angular position transducer based on a principle quite different from the conventional practice has been devised in the present invention. .It will realize high accuracy but utilize a simple construction which consists of a stator core with both exciting and output windings and a rotor core carrying no windings.
The object of the present invention is to provide an angular position transducer with practically acceptable accuracy and a simple construction without windings on the rotor core.